Summary

Evidence is presented for the formation of a small peptide conjugate following hydroxylation of 7,12-dimethylbenz(a)anthracene by rat liver preparations. This product accounts for a high percentage of the water-soluble radioactivity when 7,12-dimethylbenz(a)anthracene-12-14C is incubated with microsomes in the presence of the soluble fraction of the cell. Mainly, protein- (or nucleic acid-) bound metabolites are obtained with the microsomes alone. The addition of glutathione to the microsomal fraction increases the yield of water-soluble products in rats pretreated with 3-methylcholanthrene, but is without effect in normal animals. The action of various inhibitors has also been investigated, and it is proposed that the type of conjugate formed depends on whether DMBA is hydroxylated primarily in the side chain (normal rats) or in the nucleus (3-methylcholanthrene-treated rats).

Footnotes

↵1 This work was supported by the National Cancer Institute of Canada.

↵2 Holder of a National Cancer Institute of Canada Research Studentship.